2002 Peugeot 206 206 stop warninglight

Hi my pug 206 is doing my head in the Red STOP warning light under the speedo keeps flashing up and disapearing. It seems to be geting more and more frequent anything can set it off particuarly when siting at a uphill junction it will start and then when i move off onto a flat surface it goes away also it has taken a disliken to 4th gear as sometimes if the revs drop to low it will set it off. My engine management light is on also however this hasnt ever been a problem apart from the exhaust sounds alittle noisey now it does say in the manuel that the EML can eventually cause damage the cat in some way. Going to be taking it to garage soon but was just looking for alittle heads up before i do cheers guys, Dave